*sigh*... Manually focusing 50mm on D40

[xxpinballxx]

just a note.....
When I had my D40 and first got the 50mm I thought of packing it away too but decided to give myself a goal with it. I attached it and told myself i woudn't take it off for a week and at the time I was shooting a few hundred shots a day. I went on walks and not only did it MAKE me learn it but gave me some of my greatest shots by weeks end.

DOnt give up you'll get it.......give yourself little experiements like shooting a subject from different distances in different lighting situations and see if you can create good images in each scenario.

[daft_biker]

Originally Posted by morts

Quick tip for portraits:

compose your shot any old way and use the focus indicators to focus on either one or both eyes of your subject. Once in focus, recompose the shot how you want it to end up and take the photo.

That gives you out of focus shots, particularly at wide aperertures on SLRs.

Say I used the centre point to focus on a model's eyes and then tilted the camera down the point of focus would now be behind where I wanted it. Unless you are using a tilt and shift lens the plane of focus is parallel to the film plane (or the sensor).....tilt the camera and you tilt the plane of focus.

In my opinion correct technique on a SLR would be manually focussing or using a focus point in the right place.

Focus and recompose has it's uses but using a 50mm at wide apertures on DSLR isn't one of them.

[SandeeWig]

Originally Posted by daft_biker

That gives you out of focus shots, particularly at wide aperertures on SLRs.

Say I used the centre point to focus on a model's eyes and then tilted the camera down the point of focus would now be behind where I wanted it. Unless you are using a tilt and shift lens the plane of focus is parallel to the film plane (or the sensor).....tilt the camera and you tilt the plane of focus.

In my opinion correct technique on a SLR would be manually focussing or using a focus point in the right place.

Focus and recompose has it's uses but using a 50mm at wide apertures on DSLR isn't one of them.

Is this true for practically any lens? For example, an 18-55mm IS kit lens?

If so, what you're saying is to select the proper focus point (i.e. if you have 9 points, select the one closest to what you want in focus), vs. focusing at center then repositioning camera to the composition you want. Yes??

Second question is...if you manually focus from 2 ft. away, how can you tell if the eyes are the sharpest focus vs. the nose, for example? It's not necessarily easy to tell in the viewfinder. What do you do then?

Thanks and good thread.

[Mr Guy]

Originally Posted by SandeeWig

Is this true for practically any lens? For example, an 18-55mm IS kit lens?

If so, what you're saying is to select the proper focus point (i.e. if you have 9 points, select the one closest to what you want in focus), vs. focusing at center then repositioning camera to the composition you want. Yes??

Second question is...if you manually focus from 2 ft. away, how can you tell if the eyes are the sharpest focus vs. the nose, for example? It's not necessarily easy to tell in the viewfinder. What do you do then?

Thanks and good thread.

No, it's not, as I covered in your other thread. It's only true when the difference in the hypotenuse to the long side of the triangle is larger than the depth of field. I take it back, I don't think it's right at all, the way it's stated.

The focal length is completely unchanged when pivoting the sensor (assuming you could perfectly). It does not get longer or shorter as you move it, think of it as an imaginary broom handle extending from your lens. If you could, in this painful and somewhat disturbing example, place one end of the broom handle on the eyeball and the other against your lens, and then rotate it to point the broom handle somewhere else, the broom handle doesn't magically get longer or shorter unless you change it. Similarly, the only real change to the focal distance is the tiny amount caused by the light being diffracted through the end of the lens, so the real distance you're calculating is the one between the eyes and the end of the lens in both positions. In real world terms, you'd have to be so ridiculously close for this to make any bit of difference as to be meaningless. Macro photographers MAY care, and even then I'm not entirely sure. The real worry is that the error in your ability to perfectly rotate the camera about the sensor will introduce error larger than your depth of field, and that'll only matter for extremely narrow ranges.

[morts]

Originally Posted by daft_biker

That gives you out of focus shots, particularly at wide aperertures on SLRs.

Say I used the centre point to focus on a model's eyes and then tilted the camera down the point of focus would now be behind where I wanted it. Unless you are using a tilt and shift lens the plane of focus is parallel to the film plane (or the sensor).....tilt the camera and you tilt the plane of focus.

In my opinion correct technique on a SLR would be manually focussing or using a focus point in the right place.

Focus and recompose has it's uses but using a 50mm at wide apertures on DSLR isn't one of them.

You're right in principle

If the change is small enough, the difference isn't that great and is generally not noticeable.

Just to clarify:

The reason I suggested using the centre focus point is that it's what I'm used to. There is no reason whatsoever that you couldn't compose your shot how you wanted in the first place and use one of the other AF points to focus the shot! I just use the centre AF point out of habit!

[wulf]

I think it is fair to say that the focus and recompose method becomes increasingly problematic as the DoF becomes narrower. If you are in that range where the eyes can be sharp and the tip of the nose soft a small amount of repositioning could throw you out. Arguably though, you might be better served by stopping down the aperture a bit anyway because that blurry nose will probably detract from the result even if the eyes are perfect.

It is definitely worth learning how to switch between your AF points (easy on the D40 because there are only three of them!).

Wulf

[daft_biker]

Originally Posted by wulf

I think it is fair to say that the focus and recompose method becomes increasingly problematic as the DoF becomes narrower.

I think it's very fair to say that

[daft_biker]

Originally Posted by SandeeWig

Is this true for practically any lens? For example, an 18-55mm IS kit lens?

If so, what you're saying is to select the proper focus point (i.e. if you have 9 points, select the one closest to what you want in focus), vs. focusing at center then repositioning camera to the composition you want. Yes??

Second question is...if you manually focus from 2 ft. away, how can you tell if the eyes are the sharpest focus vs. the nose, for example? It's not necessarily easy to tell in the viewfinder. What do you do then?

Thanks and good thread.

Hi Aimee, yes to it being true for any lens but you'll probably only notice it when using large maximum apertures (like f/1.8) or in macro as you have really narrow DoF there too.

How do you tell whats in focus? On a standard zoom lens I think I'd struggle too.....I find it can be a lot trickier to manually focus a zoom lens than a prime lens (even when it's an expensive 24-70/2.8 L). Practice lots

[morts]

Originally Posted by daft_biker

How do you tell whats in focus?

Assuming you have your diopter set right, you should be able to tell by looking at the photo.
If it's dark or unclear, I use a point of reference like hair strands or eyelashes or some equally fine detail in the frame where you can instantly tell when it is in focus.

Alternatively, if there is sufficient light, hold down the shutter button halfway like you would to engage the AF without taking the shot and the focus points will flash/beep/etc when whatever they're on is in focus!

[wulf]

Even with the diopter perfectly set, it can be hard to judge focus because the viewfinder screen is pretty tiny. Also, you can't always trust the autofocus indicator - great most of the time but it can make mistakes (for example, if you are trying to focus on a strand of hair and it keeps on looking at the background).

It often helps to review the image on the LCD, zooming to the point where one pixel on the LCD = 1 pixel on the image. Also, take several shots with minor adjustments. It is better to have pictures to throw away rather than only taking one exposure of a beautiful scene and then discovering that, when viewed on your computer, the focus was wrong.

Wulf